diff --git a/video/rtp_video_stream_receiver2.cc b/video/rtp_video_stream_receiver2.cc
index e9cdde0ce7..75e71cdafa 100644
--- a/video/rtp_video_stream_receiver2.cc
+++ b/video/rtp_video_stream_receiver2.cc
@@ -719,6 +719,7 @@ bool RtpVideoStreamReceiver2::IsDecryptable() const {
 // RTC_RUN_ON(packet_sequence_checker_)
 void RtpVideoStreamReceiver2::OnInsertedPacket(
     video_coding::PacketBuffer::InsertResult result) {
+  RTC_DCHECK_RUN_ON(&worker_task_checker_);
   video_coding::PacketBuffer::Packet* first_packet = nullptr;
   int max_nack_count;
   int64_t min_recv_time;
@@ -942,6 +943,7 @@ void RtpVideoStreamReceiver2::ManageFrame(
 
 // RTC_RUN_ON(packet_sequence_checker_)
 void RtpVideoStreamReceiver2::ReceivePacket(const RtpPacketReceived& packet) {
+  RTC_DCHECK_RUN_ON(&worker_task_checker_);
   if (packet.payload_size() == 0) {
     // Padding or keep-alive packet.
     // TODO(nisse): Could drop empty packets earlier, but need to figure out how
@@ -992,6 +994,8 @@ void RtpVideoStreamReceiver2::ParseAndHandleEncapsulatingHeader(
 // correctly calculate frame references.
 // RTC_RUN_ON(packet_sequence_checker_)
 void RtpVideoStreamReceiver2::NotifyReceiverOfEmptyPacket(uint16_t seq_num) {
+  RTC_DCHECK_RUN_ON(&worker_task_checker_);
+
   OnCompleteFrames(reference_finder_->PaddingReceived(seq_num));
 
   OnInsertedPacket(packet_buffer_.InsertPadding(seq_num));
@@ -1126,6 +1130,8 @@ void RtpVideoStreamReceiver2::UpdateHistograms() {
 
 // RTC_RUN_ON(packet_sequence_checker_)
 void RtpVideoStreamReceiver2::InsertSpsPpsIntoTracker(uint8_t payload_type) {
+  RTC_DCHECK_RUN_ON(&worker_task_checker_);
+
   auto codec_params_it = pt_codec_params_.find(payload_type);
   if (codec_params_it == pt_codec_params_.end())
     return;
diff --git a/video/rtp_video_stream_receiver2.h b/video/rtp_video_stream_receiver2.h
index 78b8177372..0c7e826189 100644
--- a/video/rtp_video_stream_receiver2.h
+++ b/video/rtp_video_stream_receiver2.h
@@ -153,7 +153,10 @@ class RtpVideoStreamReceiver2 : public LossNotificationSender,
   // Decryption not SRTP.
   bool IsDecryptable() const;
 
-  // Don't use, still experimental.
+  // Request packet retransmits via NACK. Called via
+  // VideoReceiveStream2::SendNack, which gets called when
+  // RtpVideoStreamReceiver2::RtcpFeedbackBuffer's SendNack and
+  // SendBufferedRtcpFeedback methods (see `rtcp_feedback_buffer_` below).
   void RequestPacketRetransmit(const std::vector<uint16_t>& sequence_numbers);
 
   // Implements OnDecryptedFrameCallback.